Another Bachelor Party of Long Horned Bees

sleeping bees, second attempt Hi – We love your site, and have gotten lots of good information and identifications from it before. Thank you so much. I’m sending this again, because my embedded photo didn’t show up in my email for some reason. Thanks! Here’s the current question – we live in east of the San Francisco Bay area of California (but not as far east as the Central Valley). At a wildflower garden that I maintain at a school site, we’ve noticed bees congregating on the poppy seed heads about sundown. By dusk, there are several bees per stem, all faced head-down. They are non-aggressive – just seem to jockey for position. I think they are some sort of mason bee, but this behavior has me puzzled….any ideas? Can you confirm the identification in these pictures? thanks so much – keep up the good work!! gardenchien”…. I’ll try to embed the photo, and a link to try to make sure it all goes through….

Hi gardenchien, Your original letter was on the back burner from yesterday while we attempted to locate an image of an amazing fly we wanted to post from the day before. These are male Long-Horned Bees in the tribe Eucerini. We have posted several images in the past of this group roosting behavior known as Bachelor Parties. According to a posting on BugGuide, Doug Yanega indicates that the parties may contain multiple species. At any rate, exact species identification is way beyond our means.